The present invention relates to retroreflective sheeting and, more particularly, to retroreflective sheeting useful for various signs such as road signs, guide signs, and xe2x80x9cUnder Constructionxe2x80x9d signs.
A retroreflective sheet which reflects incident light toward the light source has been well known, and its excellent visibility in the night ascribed to the reflection performance has been taken advantage of in various technical fields. For example, road signs, xe2x80x9cUnder Constructionxe2x80x9d signs, etc. made of retroreflective sheeting have excellent characteristics such that they reflect the light from a light source, for example, headlights of a running car, in the direction toward the light source, i.e., toward the running car in the night to provide excellent visibility for sign viewers, i.e., car drivers.
Characters or figures for giving information are formed on the retroreflective sheet by screen printing directly on a reflective base or pasting pieces cut out of films to the reflective base. In Japan, for example, warning signs are made by screen printing characters or figures on a white retroreflective sheet, and road signs are prepared by pasting characters or figures cut out of white retroreflective sheeting to a green reflective base for expressways or a blue reflective base for general roads. Making of signs involving such a combination of different operations requires a lot of time and labor to form characters or figures. It has therefore been demanded to develop retroreflective sheeting on which highly visible characters or figures for information can easily be provided by cutting and peeling part of a transparent color film adhered to a retroreflective sheet by means of, for example, a computer-aided cutting machine, thereby to exclude the necessity of cut-and-paste operation or screen printing. However, retroreflective sheeting of the type in which part of a film layer is cut out therefrom generally has such problems that: the film layer having a high peel strength would be difficult to remove, making it difficult to form characters or figures; and the film layer having a partially reduced peel strength for the purpose of easy removal thereof would peel off during use.
Related art pertaining to this type of retroreflective sheeting includes retroreflective sheeting disclosed in U.S. Pat. No. 4,268,117 which comprises a base retroreflective sheeting and a film provided thereon via an adhesive layer composed of a pressure-sensitive adhesive layer and a heat-susceptible adhesive layer; and retroreflective sheeting disclosed in U.S. Pat. No. 4,085,314 which comprises a retroreflective base sheet and a cover film provided thereon via an adhesive layer, the cover film having been partially precut. Production of the retroreflective sheeting having two kinds of adhesive layers involves two steps for forming the adhesive layers and needs wise selection of the two kinds of adhesives.
Accordingly, an object of the present invention is to provide retroreflective sheeting which is capable of easily forming characters or figures with excellent visibility for giving information and of which the film layer hardly peels off during use.
The present invention relates to retroreflective sheeting comprising a reflective base, a transparent film layer which is colored different from the color of reflected light of said reflective base and a layer of a pressure-sensitive adhesive, said transparent film layer being removably provided on said reflective base via said layer of said pressure-sensitive adhesive, part of said transparent film layer being to be cut out on use so that said transparent film layer may form a desired image, the peel strength between said transparent film layer and said reflective base is 25 to 400 gf/25 mm, and, after said transparent film layer is pressed to said reflective base under a pressure of 5 kgf/cm2, the peel strength between said transparent film layer and said reflective base is 700 gf/25 mm or greater.